<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let obj = {
            x: 100,
            y: 200
        }
        let objx = {
            x: 200,
            y: 400
        }
        Object.defineProperty(obj, "x", {
            get() {
                console.log("有人访问了obj");
                return objx.x
            },
            set(value) {
                console.log("有人修改了obj");
                objx.x = value
            }
        })
    </script>
</body>

</html>